ABSTRACT
Dewatered sludge cake can be processed further by pelletization. The pelletizing process heat dries the sludge to a water content of about 5%, reducing the volume of the dewatered cake by a factor of roughly 15. The resulting sludge product can be bagged and distributed across the country as a soil amendment or fertilizer. The sludge cake feed systems typically include sludge cake storage hoppers, enclosed screw conveyors, and a pug mill. The dewatered cake is transferred by screw conveyor from the storage hopper to the pug mill, along with the dried material from the recycle bin. The pelletizing process requires a substantial amount of equipment and is a capital-intensive method of processing sludge. Sludge pellets can be exploited for their organic nutrient base rather than their fertilizer value. This market includes plant growth media, mulches, composts, and other landscape products.
